v2023.03.31

The March release improves strength by fixing bug, but also reworks time management:

• work around Arena bug by writing to stdout as little as possible
• always encode correct mate distance in evaluation, even when retrieving from transposition table
  • this has the unfortunate side effect of causing more timeouts
  • also some of the mates are so deep they don't seem plausible
  • mate distance encoding: because mates beyond depth 100 are found, encode M1 as 199.99 instead of 299
• now no more illegal moves should ever get played
  • fix bugs in is_pseudo_legal and add unit test
  • also check transposition table moves for legality
• big fix: fix undefined behavior due to KILLER_TABLE being too small
• time use: use time based on move number (use less time in the opening and more in the middlegame)

v2023.01.15

• Check pseudo-legality of moves fetched from transposition table (fixes illegal move bug)
• Always store search results in transposition table
• Fix side-to-move in setboard
• Fix rare bug where 8-bit search depth could overflow
• Add version info to uci command

v2022.12.29

• Enabled Principal Variation Search
• Fixed en passant bug for null move pruning

v2022.12.27

• Added Null Move Pruning

v2022.12.01

Initial release. See README.md.

• *linux64 was built on x64 Linux
• *windows64.exe was built on x64 Linux with Windows target using MinGW, and appears faster, so prefer this .exe on Windows
• *windows64_small.exe was built on x64 Windows